Engine



Se t. 20, 1949, w. N. WRIGHT 2,482,136

ENGINE Filed May 12, 1945 2 Sheets-Sheet 1 Sept. 20, 1949.

Filed May 12, 1945 W. N. WRIGHT ENGINE 2 Sheets-Sheet 2 Fay. 5.

INVENTOR.

Patented Sept. 20, 1949 UNI TED STAT-ES F l-CE 11 Claims. 1

My invention relates to reciprocatingplston engines of 'theinternal combustion type, and more particularly to suchenginesemploying drive connections between the pistons and power shaft which .afiord constant .m'echanical advantage in all positions of eachpiston lengthwise of its cylinder.

'In conventional engines incorporating pistons reciprocating in cylinders, the pistons are connected positively .toa crank shaft .by connecting rods secured tocrank arms of such shaft. Where suchmechanism is employed, however, the lever arm of the force acting on thepistonand transmitted through the connecting .rod to the crank shaft, varies. When the .piston ,-is at the top of its cylinder the effective lover arm is zero, and increases'to amaximum when the crank sha'ftihas rotated throughapproximately 90 degreesvfrom the top positioniof the piston.

My invention is concerned particularly with mechanism which will afford a constantlever arm at whichthe piston force is applied to the power shaft. The type .of mechanism which I prefer employs a rack bar for each piston-engageable with a gear arranged .to .drive the power shaft. One difficulty in mechanisms OflthiS general type waich have been proposed previously, whenapplied to a multicylinderengine, was to coordinate properly the .movement of the various pistons relative to each otherand to the power shaft. In the .case of a single cylinder engine the problem,.arose .of insuring that the piston would .21- ways follow through its complete operating cycle.

A principalnobject .of my invention, therefore, is the. provision ofnovel coordinating mechanism capable of synchronizing therotationof a power shaft with the. reciprocation .of one .ormore pistons .of an internal combustion .engine, tosupply a force for rotating the power shaft. .For accomplishing this .objectl provide simple .and effective mechanism composed .of .few parts which are .arranged compactly .and which Junction -reliably and effectively.

Itis a further object ofimy invention tolimprove to simplify :the drive connection"between'the power 's'naftand the severakpistonsof .amulticylinderen-gine, andin addition toinclude safety features which will reduce .-the..possibility of-.,engine failure.

Additional advantagescf. my .engine -.Wh-ich ar,e inherent-in the particular typeof construction which .I new preferwillbepointed .out ,in the .following description of a'representative installation. It is to be understood,..of course, that detailspf-the features show-non the-accompanyin 2 drawings ,and described .hereafter may be varied to suit'the preference of different designers, in accordance with "the ,generalprinciples of myinvention.

.Figurejl is a vertical sectional view taken transversely through a representative form of engine, along line l-I ,ofjFigure ,2, andFigure 2 is a vertical sectional view taken longitudinally throughthe engine, ,online 1-2 of Figure 1.

jFigure3is a. horizontal sectional view throu h the engine.on1line.3,,3 ofFigure l.

Figure 4"is aplan view .of a camgdrum constituting an elementof'the coordinating mechanism, and Figure ,5 is ,a jmgmentary sectional view through aportionpfsuchcam ,drum and parts cooperating with it.

As haslbeen ,pointed out above, my invention is concerned particularly with mechanism for coordinating therotationwof a power shaft with the reciprocatory movement of one or more internal combustion enginepis'tons. ,Itwill be understood, therefore,'thatthepiston and cylinder constructionandarrangementmay be conventional, and the drawing merely shows generally a representative .type ;of engine 'in which my mechanism, is incorporated. "It-is preferred, however, that the cylinders .be-arrange'd in line rather than radially.

-A..typical engine.may includev an engine block l, defining cylinders .10, ,in which pistons ll reciprocate according to-. conventional practice. In an L-Fheadtypeofengine valves 12, controlling intake and exhaustportscommunicating with the cylinders I 0, ar,e operated ,bycamson a cam shaft [3 in the .usual .way. In .an engine in which each pistonis,connectedjpositively to a crank arm .on the .crankshaitby ,a connectingrod, it is mandatorythattheucrankchaft.make .a complete revolutioneachtimeapiston.moves through an outward.. and.in.ward stroke, .or one-half a revolution for cachpistonstroke. Especially with high speed engines,-. itistherefore .usually necessary to interpose.speed.reduction;= earing between the crank shaftand .the load, .which. decreases the overall efficiency of theinstallation tosome extent.

.Inan .,engine..incorporating my mechanism ,a connectingrack 2 replaces the usual. connecting rodandgmeshes with. a gear .20 carried by the power shaft l4. As each connecting rack is driven downwardv by.a..force. applied .to its. piston, it will rotatesuchigear inthesame direction as shaft l4 rotates,. and .atthesame peripheral speed as the linear-piston speed. It .will .beevident, therefore, that the. speed at which the power shaft. is thus rotated.ascompared.to the pistonspeed, willbe ,a..-direct. function. ofthe size ,of, gear 2|]. For a given piston speed the larger the gear the slower will the power shaft M be rotated, so that the desired speed ratio may be obtained by selecting a gear 20 of proper size.

In the particular mechanism illustrated the stroke of connecting racks 2 is equal to one-quarter of the effective circumference of gears 20, so that each piston must make four strokes, two inward and two outward, for each complete revolution of shaft [4. Considered differently, the shaft turns one-quarter of a revolution for each piston stroke, half as much as in the conventional engine. During each rotation of the power shaft, therefore, each piston ll executes one power stroke, assuming the engine to be of the fourstroke cycle type. Consequently if cam shaft l3 has a single cam to actuate each valve rod it would be necessary for such shaft to be rotated at the same speed as the power shaft M. For this purpose the cam shaft may be driven by a sprocket l5 connected by a chain I6 to a sprocket I'I mounted on the power shaft. Such sprockets would, of course, be of equal size to effect rotation of the cam and power shafts at the same speed.

Each connecting rack 2 is held constantlyin mesh with its gear 20 by a backing roller 2, as shown in Figures 1 and 3. Piston II is relieved of all tilting load transversely of the power shaft 14 by connecting the rack to it by a conventional wrist pin l 8. This type of connection also guards against subjecting the connecting rack to bending loads, except those which are incidental to the compression stress in the rack.

Because each connecting rack 2 is thus maintained constantly in mesh with its drive gear 20, such gear must be oscillatable although power shaft M rotates unidirectionally. Each drive gear is therefore operatively connected to, the shaft by a ratchet or overrunning clutch, or free-wheeling unit, 2| of any suitable type. Such unidirectional drive unit effects a driving connection with the shaft as its gear 20 is rotated by downward reciprocation of the associated connecting rack, whereas the shaft can overrun such gear, and it can be rotated in the direction opposite to the shafts rotation as the connecting rack meshing with it moves upwardly, without retarding appreciably the rotative speed of the power shaft. Since various types of such unidirectional drive or overrunning clutch units suitable for this purpose are well known, it is not necessary to illustrate or describe such a unit in detail.

While each connecting rack 2 may be formed independently of all other such racks, either the bearing of the wrist pins l8 in the pistons and, in turn, the fit of the pistons in their cylinders, or special guide mechanism, would be relied upon to maintain the racks in proper registry with their coacting gears 20 lengthwise of the power shaft. I prefer that adjacent connecting racks be interconnected in pairs by rack webs or plates 22. The upper edge of each such plate is notched between the racks of its pair to receive the lower edges of the adjacent walls of the cylinders in which such racks, thus interconnected, reciprocate. Each plate insures that its racks and the two pistons connected to them willreciprocate precisely in unison.

While the power impulses on the two connecting racks of each plate 22 will occur alternately, the combined guidin action of the two pistons and their wrist pins will prevent any appreciable tendency of the plate to tilt edgewise. Moreover each connecting rack is located precisely in alignment with the center of its piston, so that the thrust force of the piston is transmitted directly to its drive gear 20. The only tendency of the rack plate 22 to tilt, therefore, would result from the drag of the piston moved downward on the intake stroke. A further advantage of such integration of adjacent connecting racks resides in the alternate emergency connection between each piston and the power shaft I4 thus afforded. If the overrunning clutch unit of one gear 20 should fail to operate properly, the thrust of the connecting rack meshing with it would be transmitted through plate 22 and the paired connecting rack integral with such plate to its gear 20.

On the compression stroke of an internal combustion engine piston considerable resistance to its movement occurs especially near the end of the stroke. When such a piston is positively secured by a connecting rod to the engine crank shaft, such crank shaft supplies power through the connecting rod to the piston to effect such compression. Since, 'in an engine incorporating my mechanism gears 20 rotate opposite to the direction of power shaft rotation during compression movement of each piston, however, the driving force required for such stroke can not be transmitted from the power shaft to the several connecting racks 2 directly through the overrunning clutch units 2| and their gears 2i).

In my engine most of the force required to effect the compression stroke of each piston is transmitted to its connecting rack from a piston moving in its power stroke even more directly than in the conventional engine. In a four-stroke cycle internal combustion engine having four cylinders, such as illustrated in the drawings, two paired pistons, interconnected through the plate 22 carrying their connecting racks, are always moving inwardly on the exhaust and compression strokes, respectively, while the other two pistons, similarly interconnected, are moving outwardly on their suction and power strokes, respectively. The power developed by the piston moving outwardly on the power stroke may be transmitted to the inwardly moving piston on the compression stroke by directly interconnecting the two rack plates 22 to effect their conjoint movement in opposite directions.

The connection between plates 22 may be a coordinating gear 23 meshing with racks 24 formed on or secured to the adjacent edges of the two plates 22, and secured on shaft 25 journaled in a stationary bearing 26, as shown best in Figure 2. As one of the pistons at the right of Figure 2 is driven downward on its power stroke part of the thrust developed by it will be transmitted through the two racks 24 and the gear 23 meshing with them to drive upward at a corresponding rate the two pistons at the left of Figure 2, one of which will be executing its compression stroke. 7

It may at first be thought that no other interconnectionbetween the oppositely moving pistons than that afforded by gear 23 and racks 24 would be required. Actually, however, in an efliciently operating engine the force necessary to complete the compression stroke of one piston exceeds that normally delivered at the same time by another piston near the end 'of its power stroke. While it is probable that the mass of the pistons, connecting racks, and rack plates 22 would usually afford sufficient momentum to complete the stroke. of the piston moving to compress a new charge, despite the ability of shaft [4 to overrun the connecting racks, it is not safe to rely upon such operation.

To insure coordination of piston movement ammo with ccontinual notation eoif power eshaft :M I rprovide eemergeney lidrive .zmechanism dzhe form of a supplemental drive between the power shaftuand the :coordinatingagear 123. :A control gear 21fisssecuredmn therendsof-shaitay2i5eremote fromc earisziisand'imeshes-zwith .ar-rcontrol-rackifl. mack is @disposed iparallel 120 power tshai-t l4 and reciprocates lengthwise off esuchashaft, being ;.guided :for such nnovement oby rchannels, michaembraceoppositeends-withemaek, formed in rfixed {guide :lonackets r29 :sunported itirom the engine :icasi-ng "as zshown in sFii u e ;;1. Reciprocation ;of wthe :ra'ck by :the mower :ishaft r-mayelae efiected by any of several 'ztypes :of .mcehanism, but: the :cam; drum :43 esecured :on :a ,control shait 3,0, :which return is ;geared pos-itively wto --shaft M,ihasnecided:zadvantages.

knack 5.128 rnecessarily rec-ipmoates synchronismcw theipistons 1| 1| so :that; likeeach piston, this :rackamust zcomplete two :strokes' in each End-irection --.while'sshaft 1 t4 dlmkes -;a single :co-znplete revolution, WhEIE the effective :length :of eeaeh connectingzrack =72 tiSafiqflaRtOZ- one equartennf -'the circumference or the gearsZU. illoefleotsuchrack movement the cam :drum :mayxhave in lit :3,

sing1e,3substantia1ly helical :return remova or equivalent isurfiace, sextending elengthwise :of the drum over;azdistancesequalto thes'stmke :efirae 28. If coordinating gear 23 andecontnolgearazl sarer ofieqnalrsize the;stroke:of the'zrackgand con- 31 :receives 2a sfollowerrplncor 1roller332 projectnrg downward from :the zbottom :of tithe 'scontnolzrack '28. Preferably the :camfdrum: isi-locatedt'directly aheneath *controh-gearfl, aseshowniimiligunes 1 "and 2 so that the 'forces 'vi illsbeitransmittedr most directlyhetween-the drum-r randzgear.

*It will be -:'evident' 'that if ime drum 23 Fhas tin it a oamgroove: making.onlyz a-eingleaaxialnmass and'ireturn-about its entire *circnmf-erence, 'itwvill reciprocate -control rack 28:once in each 'direction during a single revolution,=iv; hereas apower fl-rotates only oneihalf- =a-revol11tioh during such rack movement. The -driven gear 33 carriefi 'loy 'control shaft im therefore must'=-lee-"orily one-"half as large '-=as the driving gear n-lashing Willh fir andmarrie'd .by-sha'ft fl. "Thissgear ratio must, of course, be governed by the relationship leetween "the piston-stroke and the=rotation oft'he shaft '14 as determined' by the =size o'f gears 20,

"the relativesizes or -gears 33'=andi34 being-sueh "the piston movin'gwhrough theipowerstroke to thQ'lbBSt advantage, it is fdesirablejfor' such piston to reciprocate suiliciently rapidly so that {it will apblv'a' torque to shaft F4 as: eailyin its :stroke as is consistent "with the "avoidance "ofexces'sive accelerations in the working warts. Because of the interconnection of rack -plates fiby coordinating *gear 2-3 the "reversal of" movement 0" an thepist'onsmust-occur in' thesame period-of me.

The -contour -of the -cam groove *3 I on -drum 'shoiild'conform '"to the "type of piston *movement desired. iAattheheginningnfthezdownwardistroke 'thezspiston will hetacceleratingmnd if-ithe groove :3! ecorregpondseexactly to --the @movement of the piston when :correlated With rotation :of power =:shafit 5M, -it would. :be .pessible for a-the piston togdrivie the;,;powershaftnthrough the c0ntrol mechanism, -':-inc1ud-ing :gear 21, control track 28,:oam ;drum -3; control shaft 30,-and:gears:33 and 134,:il15t82td ;of through the i connecting slack 216i: t-liecpiston @moving through its: power :StIOkB. Incorder to.l avtoid anyapossibi-lityofthis operation, :except ifpossibly "in the case 1 of emergency, the scam ggroove :3I :-.-may be :reiieved slightly at eachiend; aseindicatedatfli :Thevcamagroove-rshould, .of course, be of true helical sha'pegover themaj or portion of its length, sozthat rthe :"zpiston working on its IJOWGIWStIQkG will-rdrive its --'gear 20 =at a rotative speed :equal toithatzofsshaft 1M. Adjecentito each end ofthe cam drum,thowevergsuchtgroove should be shaped to :allow t'he pistonsi. toz slow down While reversing their movement, and While accelerating again at the beginnin'g softheir travel in the Opposite direction. "Nevertheless the-cam :groove should be able -to contact-the followers. projection for sthe purposenf driving the .pistons'to' the-rend ofitheir strokes, if necessary, particularly fto counteract the resisting' forcecreated on :the piston 'moving through itszcompression stroke,

Assumingzthat the left'piston H showmini' Figore-2, 'isbeginning' its power stroke,:it would drive the left connecting rack 2 downward/to rotate-its overrunni-ng clutch 'z 'l and consequentlyshaftrlid, a =clockwise' direction, a's indicatedLin Figure 1. Simultaneously the two pistons atithe. right: would hedriven upward bythe rotation of coordinating gear-23 in the"counterclockwise directiongaeseen in *Figure 'Also' control gear 2'l, rotating 560E1- jointly with gear would shifticontrolirackuzil to the rightin-Figure 2 to move 'it-s' cam follower SI'a-IOIIg-the carn groove 3| of "drum '3, in-syn- 'chronism'with rotation of -=such drum by gears 33-and 3'4.

As the"resistance to upward movement ofia'qiiston 'at-the right 'of fi igure 2 increases'ibeoause :of the increasingly e greater force required Ito icompress the "fresh I charge after the exhaust mort of-thecil lin'cler at the extreme-lefthas;opene'd,:so that little "further propulsive efiort is produced, the-"speed o'fthe-pisten's travel will decrease-and shaft M will overr-irnnearsfiil! at the lettcin z-Figure 2. If this tendency of the pistons to decelerate is *greater "than permitted by ithe contour *o'fthe cam groove 3! 'in drum 53; this drumfiro- 'tated by-"shaft M throng-.1 gearing- 33, 3%,:wi'll exert a =pressure-on the follower-of raCk ZB tending to-acc'elerate' its lengthwise movement. fll'iis f or-ce "will be transmitted through gears 2'23 :and 23 to racksi for-'supn1ying theapower deficiency necessary to complete the compression of ithe new charge to drive the nistons to the=end-"o"f *theirrespe ctivestriikes.

As illustrated the drawing, the -'engine1is preferably constructed "so that the entire "power shaft assembly, 1 including gears 2- andclutches "2i may be removed as a unit, and sim'ilai'ly shaft 310 and its "cam drum 3 can be lifted. out of the engine-case as "a single a-ssen'ibly. 'It willbe understood that "various conventional engine iletails, which-"would be the samein an engine incorporating "mymechan-ism describedabove as in other engines, have not been illu'strated ortle- -scribed.

=-I' claim-*asmy invention iln an engine having a plurality or qaistons reciprocable in cylinders arranged in a row with their axes parallel, a plurality of connecting members secured, respectively, to the engine pistons, a power shaft, a plurality of rotative members carried thereby and engaged, respectively, with said connecting members, a plurality of overrunning clutches interposed between said power shaft and said rotative members, respectively, operable to effect rotation of said power shaft by rotation of said rotative members only in one direction, and a plate disposed substantially parallel to said power shaft and interconnecting two of said connecting members disposed in adjacent relationship to reciprocate in unison.

2. In an engine having a plurality of pistons reciprocable in cylinders arranged in a row with their axes parallel, a plurality of connecting racks secured to and aligned with the respective engine pistons, a power shaft, a plurality of gears carried thereby and meshing, respectively, with said connecting racks, a plurality of overrunning clutches interposed between said power shaft and said gears, respectively, operable to effect rotation of said power shaft by rotation of said gears only in one direction, and a rack plate disposed parallel to said power shaft and interconnecting two of said connecting racks disposed in adjacen relationship to reciprocate in unison.

3. In an engine having a plurality of pistons reciprocable in cylinders arranged in a row with their axes parallel, a plurality of connecting members secured, respectively, to the engine pistons, a power shaft, a plurality of rotative members carried thereby and engaged, respectively, with said connecting members, a plurality of overrunning clutches interposed between said power shaft and said rotative members, respectively, operable to effect rotation of said power shaft by rotation of said rotative members only in one direction, a plate disposed substantially parallel to said power shaft and interconnecting two of said connecting members disposed in adjacent relationship to reciprocate in unison, a second plate disposed substantially parallel to said power shaft and interconnecting two other of said connecting members disposed in adjacent relationship to reciprocate in unison, and coordinating means rotative about an axis disposed substantially perpendicular to said plates, interconnecting said two plates and operable to coordinate conjoint movement thereof in opposite directions.

4. In an engine having a pluralityoof pistons reciprocable in cylinders arranged in a row with their axes parallel, a plurality of connecting racks secured to and aligned with the respective engine pistons, a power shaft, a plurality of gears carried thereby and meshing, respectively, with said connecting racks, a plurality of overrunning clutches interposed between said power shaft and said gears, respectively, operable to effect rotation of said power shaft by rotation of said gears only in one direction, a rack plate disposed parallel to said power shaft and interconnecting two of said connecting racks disposed in adjacent relationship to reciprocate in unison, a second rack plate disposed parallel to said power shaft and interconnecting two other of said connecting racks disposed in adjacent relationship to reciprocate in unison, and located substantially coplanar with and adjacent to said first rack plate, edge racks carried by the adjacent edges of said rack plates, and a coordinating gear rotative about an axis disposed perpendicular to said rack plates, interposed between and meshing with said rack plate edge racks and operable to coordinate conjoint movement of said rack plates in opposite direc tions.

5. In an engine having a plurality of pistons reciprocable in cylinders arranged in a row with their axes parallel, a plurality of connecting members secured, respectively, to the engine pistons, a power shaft, a plurality of rotative members carried thereby and engaged, respectively, with said connecting members. a plurality of overrunnlng clutches interposed between said power shaft and said rotative members, respectively, operable to effect rotation of said power shaft by rotation of said rotative members only in one direction, plate means interconnecting two of said connecting members disposed in adjacent relationship to reciprocate in unison, second plate means interconnecting two other of said connecting members disposed in adjacent relationship to reciprocate in unison, coordinating means interconnecting said two plate means and operable to coordinate conjoint movement thereof in opposite directions, and control means separate from said overrunning clutches and operatively interconnecting said coordinating means and said power shaft for synchronizing movement of said coor-' dinating means, and consequently of said connecting members, with rotation of said power shaft at all times.

6. In an engine having a plurality ofpistons reciprocable in cylinders, a plurality of connecting racks secured, respectively, to the engine pistons, a power shaft, a plurality of gears carried thereby and meshing, respectively, with said connecting racks, a plurality of overrunning clutches interposed between said power shaft and said gears, respectively, operable to effect rotation of said power shaft by rotation of said gears only in one direction, a rack plate interconnecting two of said connecting racks disposed in adjacent relationship to reciprocate in unison, a second rack plate interconnecting two other of said connecting racks disposed in adjacent relationship to rec'iprocate in unison, and located substantially coplanar with and adjacent to said first rack plate, edge racks carried by the adjacent edges of said rack plates, a coordinating gear interposed between and meshing with said rack plate edge racks and operable to coordinate conjoint movement of said rack plates in opposite directions, means operatively connected to said coordinating gear to move therewith, means driven by said power shaft and rotatable therewith, and cam means operatively interconnecting said last two means and operable to synchronize movement thereof, and consequently to synchronize reciprocation of said connecting racks with rotation of said power shaft at all times.

7. In an engine havinga plurality of pistons reciprocable in cylinders, a plurality of connecting racks secured, respectively, to the engine pistons, a power shaft, a plurality of gearscarried thereby and meshing, respectively, with said connecting racks, a plurality of overrunning clutches interposed between said power shaft and said gears, respectively, operable to effect rotation of said power shaft by rotation of said gears only in one direction, a rack plate interconnecting two of said connecting racks disposed in adjacent relationship to reciprocate in unison, a second rack plate interconnecting two other of said connecting racks disposed in adjacent relationship to reciprocate in unison, and located substantially coplanar with and adjacent to said firstrack plate, edge racks carried by the adjacent edges of said rack plates, a coordinating gear interposed between and meshing with said rack plate edge racks and operable to coordinate conjoint movement of said rack plates in opposite directions, a control gear rotatable with said coordinating gear, a control rack meshing with said control gear and disposed generally parallel to said power shaft, a control shaft also disposed generally parallel to said power shaft, gearing interconnecting said control shaft and said power shaft to effect conjoint rotation thereof, a cam drum carried by and rotatable with said control shaft, and cam follower means carried by said control rack, engageable with said cam drum for synchronizing reciprocation of said control rack, and consequently of said connecting racks, with rotation of said power shaft at all times.

8. In an engine having a piston reciprocable in a cylinder, a power shaft, connecting means secured to such piston, unidirectional drive means interengaged between said connecting means and said power shaft, and operable to rotate said shaft by movement of said connecting means in one direction but inoperative to rotate said shaft by movement of said connecting means in the opposite direction, and control means separate from said unidirectional drive means operatively connecting said connecting means and said power shaft for synchronizing movement of said connecting means with rotation of said power shaft at all times.

9. In an engine having a piston reciprocable in a cylinder, a power shaft, connecting means secured to such piston, unidirectional drive means interengaged between said connecting means and said power shaft, and operable to rotate said shaft by movement of said connecting means in one direction but inoperative to rotate said shaft by movement of said connecting means in the opposite direction, and control means including a member operatively connected to said connecting means to move in synchronism therewith at all times, a member operatively connected to said power shaft to move in synchronism therewith at all times, and cam means operatively interconnecting said two members for synchronizing movement thereof at all times, and thereby synchronizing movement of said connecting means with rotation of said power shaft.

10. In an engine having a piston reciprocable in a cylinder, a power shaft, connecting means secured to such piston, unidirectional drive means lnterengaged between said connecting means and said power shaft, and operable to rotate said shaft by movement of said connecting means in one direction but inoperative to rotate said shaft by movement of said connecting means in the opposite direction, a control shaft, drive means interconnecting said power shaft and said control shaft to drive the latter by rotation of the former, a cam drum secured to said control shaft for rotation thereby, a follower engaged with said cam drum and reciprocated by rotation of said cam drum, and means interconnecting said follower and said connecting means and operable to synchronize reciprocation of said connecting means with movement of said follower, and consequently with rotation of said power shaft.

11. In an engine having a piston reciprocable in a cylinder, a power shaft, connecting means secured to such piston, unidirectional drive means interengaged between said connecting means and said power shaft, and operable to rotate said shaft by movement of said connecting means in one direction but inoperative to rotate said shaft by movement of said connecting means in the opposite direction, a control shaft disposed parallel to said power shaft, drive means interconnecting said power shaft and said control shaft to drive the latter by rotation of the former, a cam drum having a cam groove therein and secured to said control shaft for rotation thereby, a rack disposed parallel to said control shaft and having a follower engaged with said cam drum to effect reciprocation of said rack by rotation of said cam drum, and means interconnecting said rack and said connecting means and operable to synchronize reciprocation of said connecting means with reciprocation of said rack, and consequently with rotation of said power shaft.

WILLIAM N. WRIGHT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,271,569 Hancock July 9, 1918 1,291,642 Elwell Jan. 14, 1919 2,163,052 Niemi June 20, 1939 FOREIGN PATENTS Number Country Date 411,808 Great Britain Sept. 7, 1932 

